A dry shaving apparatus of the type initially referred to is known from Japanese Utility Model JP-2-17558 (Y2). Integrally formed on the two ends of the cap portion are narrow support arms hinged to the two narrow sides of the casing of the dry shaving apparatus both slidably and rotatably by means of a respective sliding-and-rotary joint. For this purpose, a hinge pin is resiliently carried in each of the two end walls of the casing and engages an elongated groove provided in the end walls of the support arms. The distance the guard member is allowed to slide is predetermined by the length of the grooves, that is, by abutment of the hinge pins with the end walls of the grooves. For the purpose of releasing a shaver assembly protected by the guard member, the guard member with the support arms integrally formed thereon are pushed over the shaver assembly until a pivotal motion of the support arms about the hinge pins can be effected. Following execution of such a pivotal motion through an angle of 180.degree., the guard member is located beneath the bottom wall of the dry shaver casing extending parallel to the shaver assembly, in which position it can be pushed onto the casing and locked in place. For lack of adequate space, the arrangement of the sliding-and-rotary joint in the narrow sides of the casing and the narrow support arms of the cap portion makes it necessary for the components of the sliding-and-rotary joint to be built to relatively small dimensions, with the result that the risk of breakage increases in the course of use of the dry shaving apparatus. The manipulation of a guard device mounted both slidably and rotatably on the narrow sides of a casing is difficult, resulting frequently in jamming of the engaging components of the sliding-and-rotary joint.
From U.S. Pat. No. 2,787, 830 it is known to mount a dry shaving apparatus in a disk-type casing so as to be pivotal within limits--through an angle of 90.degree., approximately--by means of hinge pins engaging in bearing shells. A segment-type interruption provided in the circular profile of the round casing serves to enable a rotary movement of the dry shaving apparatus protruding from the interruption until the shaving head is exposed for use, in addition to enabling the cord plug of a power cord to be connected with the dry shaving apparatus through the disk-type casing in order to start operation of the electric drive mechanism directly.